PROJECT SUMMARY The proposed research will advance the mechanistic understanding of dynamics in cell clusters with stable intercellular cytoplasmic bridges. This class of multicellular systems is thought to have played a role during the emergence of multicellularity and serves critical functions in present day organisms. Intercellular transport through cytoplasmic bridges gives rise to a wealth of functionally significant collective effects. One key obstacle in understanding the origins of these effects is the current lack of tractable experimental systems that can be studied quantitatively. Our research will use Drosophila oogenesis, an experimental system that provides unmatched opportunities for quantitative studies. This system relies on two types of cell clusters with cytoplasmic bridges: a germline-derived cluster containing the future oocyte and 15 nurse cells, and somatic cell clusters in the epithelium that envelops the germline cluster. Our research identified collective dynamics in both tissue types. First, we discovered that cells in the germline cluster grow in groups defined by the cluster's connectivity. Aim 1 tests the hypothesis that this growth pattern depends on intercellular transport within the cluster and reflects synchronized dynamics of endoreplication cell cycles. Second, we showed that somatic cell clusters display strong clonal dominance, a commonly observed, yet poorly understood effect during developmental growth. Aim 2 tests the hypothesis that clonal dominance emerges as a consequence of spatiotemporal coordination of mitotic cell cycles. Our work uses live imaging and computational modeling to investigate emergent dynamics in an important class of multicellular systems. Given the ubiquitous nature of cell clusters with stable cytoplasmic bridges, results of our studies will have broad impact.